It's like ....I don't want beer.....I need beer!
Just because your afraid of a 1000 doesn't mean it isn't necessary.
If you want to chop bitchez at clubs you need 1000CC+. 600CC is like showing up in a civic. You wouldn't know anything about it anyways...
Also a 600CC harley would put out like what, 9HP?
I'm planning on upgrading to a 600 SS in the next year or so, and at least now I agree with the OP's statement when it comes to SS bikes, when used on the road only. Honestly, my CBR250R does everything perfect up to around 100km/h, and the new Ninja 300R had been out a year ago (and I bought it instead), I might not have been looking to upgrade so soon or at all (although I know eventually I'd want something that could rival a real sports car in terms of performance).
With that said, if we are talking non SS, then yeah, I can definitely see more than 600 due to the hp per cc those bikes tend to put out, not to mention the increased weight.
As for the comment about 'no one needs more than a civic', realistically a 250 would be the civic in that scenario. Using cars again, the 600 SS to 1000 SS (so say CBR600RR vs S1000RR) is more like saying a M3 or even a Porsche 991 is too slow...I need a Gallardo/Veyron. Again, not knocking anyone who does go for the 1000cc SS as everyone has a right to buy whatever they can afford -- I'm simply commenting on the notion someone 'needs' (or rather requires) one.